Acetoxy Silane Flowable CVD for Low-k Gap Fill Integrity
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Solution Overview
Problem
Flowable oxide films deposited from trisilylamine in gas phase polymerization processes have high Si-H bond density and rapid wet etch rates, making them unsuitable for low-k film applications, and existing hardening processes often introduce voids and cracks due to removal of carbon and hydroxyl groups.
Innovation Solution
Depositing silicon-containing films using silicon-containing compounds with acetoxy groups, such as acyloxysilanes, acyloxyalkoxysilanes, or acyloxyaminoxysilanes, followed by in-situ plasma reaction to form a flowable liquid oligomer, which is then thermally treated and exposed to energy sources to achieve desired mechanical integrity and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trisilylamine is used as precursor in gas phase polymerization, then silicon-containing film can be deposited, but the film has high Si-H bond density and rapid wet etch rates making it unsuitable for low-k applications
Solution Approach 1:
The patent changes the chemical parameters of the precursor by using acetoxy groups instead of amine groups. This fundamental chemical parameter change transforms the deposition mechanism from gas phase polymerization to a process that forms silicon oxide networks with different bonding characteristics, thereby reducing Si-H bond density and wet etch rates while maintaining film deposition capability
Solution Approach 2:
The acetoxy groups serve as temporary functional groups that are removed during thermal treatment. These groups are intentionally introduced as short-lived intermediates that facilitate the formation of the desired low-k film structure, then are eliminated in the hardening process to achieve the final low-Si-H bond density structure
2Manufacturing precision
If hardening processes are applied to remove carbon and hydroxyl groups, then film density is improved, but voids and cracks are introduced
Solution Approach 1:
The patent performs preliminary carbon doping during the deposition process itself, incorporating carbon into the silicon oxide network before hardening. This preliminary action ensures uniform carbon distribution throughout the film matrix, which then acts as a structural support during subsequent hardening, preventing void formation while achieving the desired low dielectric constant
Solution Approach 2:
The patent creates a composite silicon oxide-carbon network structure where carbon is integrated into the film matrix rather than being a separate phase. This composite structure provides both the low dielectric constant required for low-k applications and structural integrity during hardening, preventing crack formation while improving film density
3Reliability
If carbon is added to the network to lower dielectric constant, then low-k properties are achieved, but film mechanical integrity may be compromised
Solution Approach 1:
The patent applies local quality by distributing carbon heteroatoms at specific locations within the silicon oxide network rather than using bulk carbon additions. The carbon is incorporated at the molecular level during deposition, creating localized modifications to the network structure that lower the dielectric constant while maintaining overall network connectivity and mechanical integrity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces silicon-containing films with mechanical integrity, porosity, and dielectric constants suitable for low-k applications, providing a void-free gap fill with improved mechanical properties and reduced etch rates.
Implementation Method 1
introducing said at least one silicon-containing compound into a reactor and reacting said at least one silicon-containing compound in-situ with plasma to form a flowable liquid oligomer
Implementation Method 2
Flowable chemical vapor deposition (FCVD) processes
Implementation Method 3
subjecting the coating to a thermal treatment at one or more temperatures between about 100 °C to about 1000 °C to density at least a portion of the coating and form a hardened layer
Implementation Method 4
exposing the hardened layer to energy selected from the group consisting of a plasma, infrared light, chemical treatment, an electron beam, or UV light to form the final silicon-containing film
Data Source
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AI summary
A method for depositing a silicon-containing film, the method comprising: placing a substrate comprising at least one surface feature into a flowable CVD reactor which is at a temperature of from about -20 °C to about 400 °C; introducing into the reactor at least one silicon-containing compound having at least one acetoxy group to at least partially react the at least one silicon-containing compound to form a flowable liquid oligomer wherein the flowable liquid oligomer forms a silicon oxide coating on the substrate and at least partially fills at least a portion of the at least one surface feature. Once cured, the silicon oxide coating has a low k and excellent mechanical properties.